The objective of this research is to study RNA phosphorylation steps in the eucaryotic nucleus and to evaluate their function in RNA processing. The approach in the study of the polynucleotide (RNA) kinase reactions will be two-fold in the time covered by this proposal and will utilize partially purified nuclear systems: 1. Study of the phosphorylated structures and their appearance in identifiable RNA classes: a. Comparison of in vitro phosphorylated 5' termini from poly A plus and poly A minus RNA. b. Measure of temporal appearance of these 5' termini in different classes of RNA. c. Study of relationship of the phosphorylation steps to RNA synthesis. d. Study of relationship of RNA phosphorylation to RNA splicing. 2. Study of the enzymatic activity responsibe for the polynucleotide kinase reaction involving RNA. The following areas of research will be undertaken: a. Specificity of activity will be measured by exogeneous substrates. b. Partial purification of the activity will be undertaken. c. RNA polynucleotide kinase will be compared with the DNA polynucleotide kinase from eucaryotic nuclei.